This invention relates to an axial piston fluid engine with single-acting cylinders pivotally attached to rotary valves that are actuated by a wobble drive member.
Axial piston steam engines of the type having a plurality of pistons along parallel axes pivotally operated by a wobble plate mechanism are known in the art. An example may be seen in U.S. Pat. No. 4,491,057 (Ziegler, 1985). As in other examples such as U.S. Pat. No. 4,106,354 (Girodin, 1978), the engines are encased in a rigid block and have fixed, stationary cylinders. The pistons have ball-jointed piston rods that push and pull a wobble plate mechanism to convert the piston motion into rotary movement.
The engines in these examples have many precisely machined parts and castings as well as an engine block for encasement. The engines are relatively heavy for the power they can produce. The pistons are subject to side pressures from the angular piston rod alignment. Additional piston extensions and seals are needed to accommodate the ball-jointed rods attached to the pistons. Side forces associated with angular piston rod alignment cause pressure against the sides of the pistons and the connecting rods to the wobble plate. The pressure on the pistons, joints and seals require frequent lubrication in places that are not easily accessible. Worn seals and joints are not easily replaced.
No such engine has been adopted for use on a wide scale. The lack of commercial exploitation of this type of engine is probably due to the relative high cost of manufacture as well as maintenance and lubrication issues. Scaling for large and small engines may also be problematic due to the confined space for valve plumbing and actuation. The space restraints between the cylinders prescribe small port openings with restricted gas flow.